BRPI0110803B1 - Method, device and security system, all for authentication of a dial - Google Patents

Abstract

The invention refers to a method, device and security system, all for authenticating a marking (M-P), comprising the steps of: exciting said luminescent probe marking (M-P) with at least one excitation pulse (P) of at least one excitation source (3, 31 - 36), measuring probe intensity values (VP1 - VPn) of emission intensity (I) from emission radiation (E) of said luminescent probe marking (M-P) in response to said at least one excitation pulse (P) at time intervals (t1 - tn) , forming a probe intensity-versus-time emission function of said probe intensity values (VP1 - VPn) , comparing said probe intensity-versus-time emission function with at least one reference intensity-versus-time emission function, said probe intensity-versus-time emission function and said reference intensity-versus-time emission function are normalized prior to comparison. <IMAGE>

Description

Report of the Invention Patent for "METHOD, DEVICE AND SAFETY SYSTEM, ALL FOR AUTHENTICATION OF A MARKING".

FIELD OF THE INVENTION The invention is in the field of security markings applied by inks or coating compositions or on loose materials, and documents or articles carrying such security markings. It relates to a novel method for exploring the characteristics of certain luminescent pigments incorporated into said inks, coating compositions or articles. In particular, it deals with a method and a device for exploiting the luminescent characteristic of early afternoon glow of certain luminescent materials and luminescent compounds and proposes a security system for tagging and authenticating an item. Background of the Invention Luminescent materials are among the classic ingredients of safety coatings or paints. They convert the energy of an excitation radiation of a given wavelength into light emitted from another wavelength. The exploited luminescent emission may be in the UV range (below 400 nm), the visible range (400 - 700 nm) or the near infrared range (700 - 2500 nm) of the electromagnetic spectrum. Certain luminescent materials may emit simultaneously at more than one wavelength. Most luminescent materials can be excited at more than one wavelength.

If the emitted radiation has a longer wavelength than the excitation radiation, someone speaks of "Power" or "Downconversion" luminescence. If the emitted radiation has a shorter wavelength than the excitation radiation, someone speaks of "antifeed" or "upconversion" luminescence. Luminescence can be of two different types: fluorescence or phosphorescence. Fluorescence is the ready emission of radiation with excitation, while phosphorescence is the delayed emission of radiation, observable after excitation has been interrupted. Phosphorescence, also called early afternoon brightness, is characterized by a specific decrease in luminescence intensity as a function of time; The corresponding material-specific durations may vary from nanoseconds to the multi-hour time scale.

Luminescent materials may be organic or inorganic in nature. Examples of the former are cyanine-like molecules, as well as coumarins, rhodamines, etc. Examples of the latter are copper or silver doped zinc sulfides, rare earth doped yttrium aluminum grenades or yttrium vanadates, etc. Another class of luminescent can be found among metallorganic compounds, for example silicon phthalocyanines, rare earth beta-diquetonates, etc.

Luminescent materials can be used in paints or coatings as both pigments and soluble materials. More recent developments have made luminescent pigments available in colloidal form. Particular applications also rely on luminescent polymers, obtained by polymerization, copolymerization or grafting of luminescent molecules into or on a polymer chain.

All of these compound classes and application forms have been used in safety compositions and for safety purposes. Corresponding detection equipment may be manufactured to discriminate between ready luminescence (fluorescence) or delayed luminescence (phosphorescence). US 3,473,027 deals with the general use of organic and inorganic rare earth compounds as visible and IR luminescent markers for applications such as goods and label identification, personal identification, identification and registration of passing vehicles, machine reading of information, ZIP codes, invoices, labels, etc. and high capacity storage devices. The patent also describes a "spectroscopic detector" for discriminating between different strict line luminescent responses. US 3,412,245 adds the luminescence drop time characteristics in the coding factors. In this way, rare earth-based luminescents having millisecond drop times can be distinguished from faster-falling organic fluorescent material. Discrimination is achieved by excitation with sine-wave or modulated UV light sources using variable modulation or pulse frequency in conjunction with spectral separation of the different emission wavelengths. US 3,582,623 and US 3,663,813 disclose further developments of spectroscopic detection equipment for luminescent aspects. US 3,650,400 describes the use of a pulse light source, in conjunction with synchronous pulse rate detection ("lock-in" principle), to suppress the influence of ambient light. By this method, the detector is only sensitive to the appropriate luminescent response. The major drawback of prior art methods, which rely on determining the modulation transfer function of the material, is their inherent slowness. For these reasons, they are not typically implemented on high speed authentication machines. US 4,047,033 describes the use of an upward converting luminescent material for safety purposes as well as corresponding detection equipment. The detection features excitation with an IR GaAs LED, emitting at 950 nm wavelength in continuous or pulsed mode, combined with spectroscopic identification of luminescent emission. Reference is made to the indirect feature, measuring pulse lag, to estimate the rise and fall times characteristic of the luminescent response. This method, however, is strongly affected by variations in luminescence intensity, and is therefore not easy to implement in practice.

Another prior art method suitable for high-speed authentication is pulse excitation of a moving test sample on a conveyor belt. After passing from the UV excitation source, the intensity of the induced luminescence falls according to the intrinsic falling characteristics of the material. One or more photodetectors, placed at specified distances from the UV source along the conveyor belt, are used to estimate the specific points of said drop characteristics. The main disadvantage of this method is its limitation to such phosphorescent materials which have characteristic luminescence drop times of the order of 50 milliseconds. This limitation is a consequence of the mechanical constraints (conveyor belt speed) of the detection process. It is an object of the present invention to provide a safety method, device and system that overcomes the drawbacks of the prior art. In particular, the invention should allow rapid sampling of the luminescence drop characteristic and should therefore be suitable for high speed machine reading applications.

In addition, the invention should allow a wide choice of upward or downward conversion phosphorescent materials having drop times from sub-microseconds to ten milliseconds or greater. A further particular object of the invention is to make the authentication process more reliable by compensating for changes in luminescence intensity, which may occur due to changes in the luminescent marking itself (aging, dirt) or measuring equipment.

SUMMARY OF THE INVENTION The above objectives are primarily achieved by a method, device and security system for authenticating a luminescent test mark and in accordance with the independent claims. The invention is based on a comparison of the time-dependent luminescence emission functions of a test material with that of a reference material. Therefore, according to the invention, curve shapes are used as the authentication aspect, rather than the intensity values of the individual measurements. Said emission functions are compared in standard form. In doing so, the comparison becomes largely independent of intensity deviations due to aging, alteration, or dirt. The invention further provides direct evaluation of the time-dependent luminescence emission function of a test mark following pulse excitation. The luminescent can here be excited using any kind of intense pulsed radiation source, for example light emitting diodes, laser diodes, Q-switched lasers and light sources derived from them by nonlinear optics as well as lightning pulses. X or particle beams, in particular pulsed electronic beams. After excitation with an appropriate excitation pulse, preferably with a light pulse of appropriate wavelength and duration, the luminescent material emits part of the absorbed energy in the form of emission radiation of a second wavelength. In some cases, said radiation emission occurs almost immediately, and stops with the interruption of excitation. In other cases, the emission is delayed in time and the intensity of the emitted radiation follows a simple exponential fall law or more complicated hyperbolic laws or even shows a rise and fall behavior, representative of the complicated processes of internal energy transfer. and competing fall mechanisms. In each case, however, the observed evolution of emission intensity as a function of time after the end of external stimulation depends only on the luminescent material itself, and thus serves as an authentication aspect, indicating the presence of said specific material. Even if the absolute luminescence intensity is reduced, for example by aging or dirtiness of the material, the shape of the emission versus time function is preserved, as is typical for a luminescent compound.

In the context of this invention, the drop or fall curve must mean any specific intensity versus time function of a test and its reference. Such an intensity versus time function represents the measured response of the intensity of luminescence emission due to an exciting pulse. The term "source of excitation" should in addition apply to the electromagnetic radiation source having a wavelength between 200 nm and 2,500 nm, including UV light, visible light and short wavelength IR light. (non-termko). Alternative methods of stimulation using, for example, x-ray or electron beam pulses are possible and included by said definition as well.

In carrying out the method and use of the authentication device, the intensity of the issuance of a test is sampled at appropriate time intervals and stored in an analog memory, for example digitized by an analog to digital (AD) converter and stored in a Digital memory

A luminescent emission reference curve as a function of time, taken from a reference sample using the same instrumental configuration and procedure, is stored in a digital memory, too, and provided for comparison and authentication. Authentication of a test under test is performed by a point-to-point comparison of its luminescence drop curve with the stored reference sample drop curve.

The issuing functions of the proof and reference are compared in the standard way. Normalization implies that the intensity values of both emission functions are scaled such that the highest values of both drop curves coincide.

If said comparison of the proof drop curve with the corresponding reference drop curve confirms the identity within definable tolerances, a compliance signal is produced to authenticate the proof. In the opposite case, nonconformity is assumed. The sign! Compliance or non-compliance may be any electrical, optical, acoustic or other signal. Said definable tolerance can be designed on a point by point basis, ie each point on the test curve is compared with its point on the corresponding reference curve and must be within absolute limits (eg + 50 / - 30), relative (eg ± 20%) or individually defined from that point on the reference curve. On a point-by-point basis, all points must be within their respective tolerances for the test sample to be accepted.

Alternatively, a general tolerance criterion may be applied; that is, the individual differences in the corresponding test and reference intensities, or some convenient function of them such as squares or absolute values, etc., are summed over all points, and the resulting sum is verified against said criterion. general tolerance. The method of the invention has the advantage of being applicable to any kind of luminescence drop characteristics, whether exponential or not. In particular, it is applicable for authentication of luminescent mixtures having the same particular luminescent center in environments with different drop characteristics. For example, a mixture of YV04: Me and Y202S: I can be distinguished in this way from their unique components. The method according to the invention can be designed such that a "one-time trial" measurement ie a single excitation light pulse followed by the acquisition of the corresponding luminescence response as a function of time, lasting on the order of one millisecond It is sufficient to collect the complete information of the luminescence drop of a test and compare it with the reference data. Therefore, high speed operation in fast moving samples is here guaranteed.

However, in the case of poor luminescence, ie insufficient signal to noise ratio (Y / N), the measurement may also be repeated a number of times and results may be averaged more than one of said "attempts" on a point by point basis to improve the S / N ratio and thus obtain the desired drop curve information with greater statistical accuracy. It is an additional advantage of the method of the present invention that it is modelless, that is, that the luminescence drop curve itself is used as the authentication aspect rather than a parameter derived from it. Parameter derivation is always linked to a physical model and becomes inapplicable in case the model does not hold. Modelless methods, therefore, have a much broader application range than modeled ones. The method according to the invention may be used in conjunction with other existing techniques for spectral identification of luminescent responses. In particular, it can be used in conjunction with spectral filters, wavelength dispersive elements, optical grids or other optical instrumentation that leads to wavelength selection. Light collecting optics can also be used to improve the signal to noise ratio of the photodetection chain.

More than one detection channel may be provided for the simultaneous detection of luminescent mixtures, or luminescence emitting at more than one wavelength simultaneously. The latter is often the case with rare earth ion-based luminescent materials. Different detection channels are provided herein with appropriate wavelength selectors, and the corresponding intensity versus time data is individually sampled and stored.

In a particular embodiment, the sensing channel is a microspectrometer unit comprising a wavelength disperser (e.g., a prism, a grid or a linearly variable filter) and a forming photodetector. The latter may be a linear photodiode formation or a linear CCD (paired charge device) formation. To ensure high operating speed, a modified two-dimensional CCD matrix formation can be used in place of linear CCD formation.

In CCD matrix formations, an image frame of photogenerated charge carriers produced by exposing the silicon chip to light is shifted vertically, line by line, to the edge of the chip, where the individual lines are then shifted "horizontally". "Read, pixel by pixel. These shifting processes are happening in parallel, and huge amounts of data can be manipulated very quickly (typical speeds for a 256 x 256 CCD formation are up to 40 MHz for pixel to pixel shifting" up to 4 MHz for the "vertical" line-to-line shift). Said modified CCD matrix formation is designed such that a first line of pixels is acting as the photodetector formation for the spectrum produced by said length spreader. Subsequent lines of pixels are protected from the influence of light and serve as an intermediate mass storage device. During this excitation, time-dependent spectral information is acquired by a rapid "vertical" line-to-line shift and stored in the CCD's light-protected area for subsequent reading by the instrument processor.

More than one excitation source may be provided so as to gain hardware flexibility for luminescent detection having different excitation wavelengths. Light-emitting diodes (LEDs) in particular are well suited for illumination of a spectral range of approximately 50 nm bandwidth. Providing a set of different LEDs allows to cover a larger spectral area of interest. This multi-LED light source can be controlled by the instrument microprocessor such that the choice of excitation wavelength can be performed by mere programming. It is of particular interest to combine said multi-LED light source with said microspectrometric detector unit to obtain a universal luminescence / drop time detector module.

According to the invention, the same equipment can be used to set the reference drop curve and to authenticate an unknown sample. The apparatus may thus be operated in a "learning mode" where a reference drop curve (function of intensity emission versus reference time) is acquired from a properly processed reference sample and the corresponding data stored in memory. The equipment can also be operated in a "test mode" where the luminescence drop curve of a test (function of intensity emission versus test time), carrying a mark to be authenticated, is acquired, the color data - respondents appropriately processed and compared to previously stored reference data to derive a compliance / non-compliance indicator. The same device would thus be operated in a "learning mode" to store reference data in memory, and later to test evidence in a "test mode". The device may also comprise more than one memory segment for providing reference data for authentication of different tags. Said "learning mode" and said "test mode" need not, however, necessarily be implemented within the same physical unit or device. In an alternative embodiment, a first device is dedicated to acquiring / defining a drop curve. The reference data is then transferred to the memory of a second similar device, which is exclusively dedicated to the authentication of the test samples. The method and equipment according to the invention may be used to authenticate inks. and / or coating compositions comprising suitable luminescent material as well as articles such as security articles or coated articles made using said inks and / or coating compositions. Said method and equipment may furthermore be used to authenticate material loose luminescent material such as paper or plastic used for the manufacture of articles such as o banknotes, security documents, identity cards, credit cards, security wires, labels and other security articles. The security system can be performed based on the sketched method by providing a reference sample set comprising luminescent materials and / or luminescent compounds of similar spectral emission (i.e. emission color) but having different time dependent emission functions. . Said reference samples are distinguishable by the method and the device according to the invention, for example by incorporating one or more of them in a tag on an item, for authentication purposes.

Examples The invention is also exemplified by the embodiments of security systems and authentication devices as described below and as shown in the following drawings: Figure 1 shows the emission spectrum of an upconverting phosphor that may be used in conjunction with the invention; Figure 2 shows the luminescence drop curves of four different upconversion luminescent matches that can be used to constitute a security system according to the invention; Figure 3 shows the block diagram of a first embodiment of an authentication device. Figure 4 shows a typical luminescence intensity / time characteristics that can be used for authentication purposes in accordance with the present invention; Figure 5 shows a schematic block diagram for a modified embodiment of a detection device according to the invention, Figure 6 shows a view A schematic diagram of a more sophisticated embodiment of a detection device according to the invention, Figure 7 shows the energy levels of the praseodymium ion (3+), Figure 8 shows a focusing network type microspectrometer mounted on a linear photodiode formation, Figure 9a shows the reading principle of a two-dimensional CCD formation, Figure 9b shows the data shift principle in a CCD formation.

A security system according to the invention comprises a microprocessor based authentication equipment as shown schematically in Figure 3.

As representative of the collection of luminescent compounds in one label, four erbium-based upconversion matches of a different nature were chosen for: Gd202S: Er, Yb; Y202S: Er, Yb; BaY2F8: Er, Yb; NaYF4: Er, Yb. At irradiation with a 950 or 980 nm light source, they all emit green near 550 nm (Figure 1). The green phosphorescent emission durations are, however, very different for the four materials as shown in Figure 2. The authentication device as shown in Figure 3 comprises a microcontroller or processor 1 configured, for example, by the MicroConverter® ADuC812 from Analog Devices. The ADuC812 chip comprises an 8052 1a 16 MHz microprocessor (CPU) with 32 digital I / O lines, a 5ps 1 b 12-bit analog / digital (A / D) converter, as well as D / A, RAM converters (256 bytes) and EE / Flash (Mem) memory or 1c memory device for program (8K) and data (640 bytes) storage. EE / Flash (Mem) 1c memory is electrically erasable permanent memory and allows the implementation of a "learning mode". The internal memory of the ADuC812 chip was supplemented in our example with 32K external random access memory (RAM) or 1d memory device. The authentication device also contains an ADuC812-controlled laser current exciter 2, a 980 nm wavelength pulse laser (LD) diode as collimator optics excitation source 3a, as well as a photodetection chain based on a commercial green-sensitive GaAsP photodiode (PD) 4, an optional optical filter 4a and a corresponding amplifier 5. The 4.5 photodetection chain is designed to ensure a minimum bandwidth of 200 kHz, corresponding to ADuC812 5μβ sampling rate; its output is connected to the ADuC812 1b A / D converter. The ADuC812 is also connected to an SLT mode switch for L / T learn / test mode selection, a push button B to start the measurement cycle, as well as the yellow, green and red LEDs 8a, 8b, 8c to indicate on / off and pass / fail states (Yes / No). Pushbutton B is turning on the main power supply of the Vdc circuit. A processor-controlled power conservation switch 9 is provided, allowing the processor to conserve its own power to complete the measurement cycle and to shut down in good condition.

In "learning mode" L, a reference drop curve or reference intensity versus time emission function is acquired. A reference sample 7-R is placed below the collimator optics 3a and optical filter 4a. After setting the SLT switch to "learning mode" L, pushbutton B is pressed, energizing the detector unit. Controlled by microprocessor 1, the excitation source laser diode 3 is addressed with a short current pulse of the laser current exciter 2 (typically 1 A for 200 με). A 980 nm laser excitation pulse P is focused by the optics of collimator 3a over a luminescent M-R reference marking of the 7-R reference sample. The corresponding luminescent response at 550 nm (emission radiation E) is sensed by photodiode 4. The photodiode signal passes into amplifier 5 and thence into A / D converter 1 b. After pulsing the laser diode, microprocessor 1 initiates a direct memory access (DMA) data acquisition sequence. During this sequence, the photodetection chain signal 4.5 is sampled at regular time intervals (e.g. every 5 ps) by the A / D converter 1b and stored at subsequent memory locations of the external memory device 1d. The sampling time and the number of samples to be taken are pre-set by the microprocessor program as a function of the previous results. After sampling is complete, data in memory device 1d is analyzed, processed, condensed to 64 data points by setting reference values VR1 to VR64 (Figure 4) and stored in microconverter permanent memory device 1 c. The function represented by the reference values VR1 to VR64 is further normalized, ie the values VR1 to VR64 are graduated from the highest value of the function. Therefore, VR1 - VR64 are independent of the general intensity variations that affect luminescent emission. Figure 4 illustrates the possible shape of this reference curve, which is maintained as a list of reference values (VR1, VR2, VR3, ...) for the corresponding points in time (t1, t2, t3, ...). . VRn values can optionally be associated with corresponding individual tolerances (Δ +, Δ-). Successful completion of the operation is recognized by the green "Yes" indicator 8b. A few seconds after the operations are completed, the microprocessor shuts down the detector unit via the power supply switch 9.

In "test mode" T a test drop curve is acquired and compared to the previously stored reference curve. According to Figure 3, a 7-P test sample comprising an M-P test mark is placed in the correct position of the sample. After setting the SLT switch to "test mode", the trigger pusher B is pressed, energizing the authentication device. The same sequence of operations as described for the "learning mode" L is performed to the point where the measured luminescence data is processed and condensed into 64 data points. The data thus obtained VP1 to VP64 are also normalized and compared to the previously stored reference values VR1 - VR64. To compare the data representing the drop curve of an MP test mark with that of an MR reference mark, the corresponding data points are subtracted from each other, and the absolute values of the differences are summed for all 64 points. of data. If the value of this sum is less than a selectable criterion, the test sample is accepted as "good" and the green "Yes" LED 8b is activated. If the value of said sum exceeds said criterion, the test sample is rejected as "bad" and the red "No" LED 8c is activated. A few seconds after operations are complete, the microprocessor shuts down the detector unit via the power supply switch 9. The emission intensity E of a 7-R reference sample or 7-P sample test may vary within a Great measure. Aging of the luminescent material or changing the surface of an M-R reference mark or an M-P proof mark is often the cause. If the marking, for example, is applied to an article 7, such as a ballot or product label, the surface of said ballot or label may be dirty or scratched. This may substantially reduce the intensity of excitation in the luminescent material and may also reduce the intensity of the emission radiation of such a marking. In particular, the emission E radiation of a 7-R reference sample may have higher absolute values than the emission E radiation of a 7-P test sample. Therefore, the method according to the invention relies on the comparison of the shapes of the drop curve rather than the individual absolute intensity values.

After normalizing both curves to their highest value between t1 and tn, two identical curves are obtained for samples containing the same luminescent even if the latter is present at a different concentration. By applying this general principle of comparing normalized curves, the authentication process will not be affected by factors resulting in intensity or measurement deviations. The number of VP1 - VPn and VR1 -VRn individual data points taken to define the CP probe curve and the CR reference curve may vary to a high degree. Higher numbers generally allow a more accurate definition of a curve.

For practical purposes, a number between 32 and 128 values, preferably 64 values, has proved sufficient.

After deriving the VR1 - VRn reference values in RAM 1d or permanent memory device 1c, these data can be transferred as VR1 - VRn reference values to other authentication devices.

Similarly, each authentication device may have a number of memory segments to store VR1 - VRn reference values for a number of different M markings. In general, VR reference values for comparison may be provided anyway; electronic data may be provided by internal or external memories, memory card, wired or wireless transmission, such as encrypted memory or data attachment in a sample or in any other suitable manner. The central processing unit of the AduC812 1a has been programmed to perform the sketched operations after pressing the pushbutton B. They remarkably comprise the following functional program blocks: ensuring power supply autonomy during the measurement cycle by turning the switch on. 9, read SLT learn / test mode switch, if in learn mode L: prepare external memory for DMA data acquisition, pulse laser diode, acquire predetermined number of DMA mode luminescent response samples in 1d memory device, postprocess the sampled data and compress it in an optimized way at 64 data points, store the compressed and normalized data, including a compression indicator, in the internal permanent data EE / Flash 1c memory device ADuC812, as a reference, if in test mode T: prepare external memory for DMA data acquisition, pulse acquire a predetermined number of luminescent response samples in DMA mode on the 1 d memory device, postprocess the sampled data and compress it into 64 normalized data points according to the previously stored compression indicator, compare the compressed and normalized data with the standard reference data previously stored in the memory device 1c, and deduce a compliance / non-compliance indicator, adjust the approved indicator / fault LEDs accordingly to show the result after a waiting period of predetermined length, turn off the power supply via switch 9.

In a modified embodiment of an authentication device according to the invention, schematically shown in Figure 5, two excitation light sources 31 and 32 for emitting excitation pulses P of different wavelengths with collimation optics 31a and 32a and former corresponding pulse citers 21 and 22 are provided. Two detection units for two different wavelengths, including collimation optics 41b and 42b, filters 41a and 42a, photodetectors 41 and 42 and amplifiers 51 and 52, are also provided. Optical elements are arranged such that all optical axes intersect at a single observation point in a 7-P test sample. Said 7-P proof sample, carrying an M-P proof mark, is carried through the authentication device. Depending on the aspect to be detected, processor 1 sends a current pulse to light source 31 or light source 32, or both. Depending on the emission to be detected, use is made of photodetector 41 and / or photodetector 42.

As an example, the device may be designed for the detection of erbium-based upconverting materials excited with an excitation source 31 at 980 nm and green emission at 550 nm that will be detected by photodetector 41, simultaneously europium luminescent which are contained in the MP probe mark, are excited by light source 32 at 370 nm and emitting close to 610 nm, which will be detected by photodetector 42. The presence of both luminescent materials is required to confirm authentication of the MP probe mark. The principles of operation of the device according to this particular embodiment are otherwise the same as those for the first embodiment.

In another particular embodiment, the device may be designed for the detection of praseodymium-based upconversion materials, which must be simultaneously excited with a first laser at 1014 nm and a second laser at 850 nm, and which subsequently emit red in approximately 600 nm (Figure 7). In the embodiment, the excitation pulses P are generated by the excitation sources 31 and 32 which are operated simultaneously. Photodetector 41 is allocated for monitoring 600 nm emission. The second photodetector 42 is designed to control the emission of the 1310 nm praseodymium downconversion, which is also present. Depending on the desired degree of complexity and luminescent properties of the M-P proof marking, even more excitation light sources and / or photodetectors may be incorporated.

In yet another more sophisticated embodiment of an authentication device according to the invention, schematically depicted in Figure 6, a combination of a multiple LED or an LD 3 excitation source, a focusing network type microspectrometer 4a 'comprising a light guide nozzle, a two-dimensional CCD formation 4b 'as a photodetector / acquisition device, and a processor 1 for controlling data acquisition, storage and evaluation are used. The excitation source 3 preferably comprises a series of 31,32,33, ..., 3n light-emitting diodes having emission wavelengths chosen to cover the visible and near-infrared portion of the UV spectrum. light. In particular, a set of commercially available LEDs emitting at 370 nm (UV), 470 nm (blue), 525 nm (turquoise), 570 nm (green), 590 nm (yellow), 610 nm (orange), 660 nm ( 700 nm (dark red), 740 nm (IR), 770 nm (IR), 810 nm (IR), 870 nm (IR), 905 nm (IR) and 950 nm (IR) proved useful. These LEDs may be arranged at the user's convenience, but are preferably arranged in a circle around the microspectrometer light guide nozzle. The focusing network type microspectrometer 4a 'is a device according to Figure 8. The probe light is joined to the focal plane of the spectrometer by an optical fiber or light guide nozzle that acts as a light source in the shape of a point, illuminating a self-focusing reflection network. The latter focuses the light back over a linear photodetector formation, scattering the different wavelength components comprised in said light over adjacent pixels of said formation. A spectrum of the test light is thus obtained by reading the pixels of the photodetector formation.

For the rapid acquisition of time-dependent spectral information, a two-dimensional paired charge device (CCD) formation 4b 'is used. Such CCD formations comprise a two-dimensional field of photosensitive pixels, which can be read by a shifting process according to Figure 9a: Pixels are first shifted "vertically", line by line, into a horizontal register. There, individual pixels are shifted "horizontally", pixel by pixel, to a preamplifier and additionally to the output. Two-dimensional CCD formations are commonly used in camcorders and can comprise between 256 and 1K pixels in each dimension. The displacement of pixel information, present as stored photogenerated electrons, is explained in Figure 9b: Three electrodes (1,2,3) are present for each pixel, which are triggered with positive three-phase clock signals (φ1, φ2, φ3). . Electrons always accumulate in cavities of positive potential, represented by an "inactive" state. The active and inactive phases of the clock signals are made to overlap to result in a displacement of the stored electrons of the entire formation by one pixel after a clock period (t1 to t6), ie: t1 t2 t3 t4 t5 t6 φ1: active active inactive inactive active inactive φ2: inactive active active inactive active inactive φ3: inactive active inactive inactive active inactive In the context of the invention, a first line of photosensitive pixels (PIX) of said two-dimensional CCD formation serves as the formation of the linear photodetector of said microspectrometer device 4a '. The remaining lines of the CCD pixels are not used as photosensors, but are protected from the influence of light and act as a primary storage device for time-dependent spectral information. Processor 1 with its memory device 1c controls the data acquisition and processing process by performing the steps of: pulse the appropriate excitation source diode or diodes 3 to excite the luminescence marking of the test sample 7 P, respectively reference sample 7-R, following the pulse of light, perform an appropriate number of line offsets in the formation of the CCD so as to record the time-dependent spectral response information as a two-dimensional image frame in the area. protected from said formation, read the time-dependent spectral response information from the CCD formation and store it in the memory device 1c, post-treat and evaluate the time-dependent spectral information collected in terms of the authentication task to be performed. The attainable time resolution is determined by the line offset frequency of step b). The latter can be as high as 4 MHz, corresponding to a time step of 250 ns. Reading the accumulated data from step c) can occur much more slowly, in a manner known to the person skilled in the art. The data available after step c) corresponds to an "image frame" having a spectral dimension and a time dimension. A time drop curve can be obtained from this table by dividing a time margin at the appropriate wavelength; This information can be treated and evaluated as given in the one-dimensional examples above. The analysis may alternatively be extended to more than one wavelength, or also combined with spectral analysis, taking advantage of the second dimension of the acquired data frame.

Claims (18)

A method for authenticating a luminescent probe (MP), comprising the steps of: excitering said luminescent probe (MP) with at least one excitation pulse (P) from at least one excitation source (3, 31 -36), measuring the intensity of the test intensity (VP1 - VPn) of the emission intensity (I) of the emission radiation (E) of said luminescent test (MP) marking in response to said at least one excitation pulse. (P) at time intervals (ti - tn), characterized in that it forms an intensity versus time emission function of said test intensity values (VP1 - VPn), comparing said intensity versus time emission function of the test. With at least one intensity versus time reference emission function, said intensity versus time emission function and said intensity versus time reference emission function are normalized prior to comparison. Method according to claim 1, characterized in that at least one luminescent test (MP) marking is part of a test sample (7-P) to be authenticated and that specific emission characteristics of said test light At least one luminescent probe (MP) marking is measured, said specific emission characteristics include at least one excitation wavelength of said excitation pulse (P), at least one emission wavelength of said emission radiation ( E) and test intensity values (VPi - VPn) of emission intensity (I) at time intervals (ti - tn) for at least one of said emission wavelengths. Method according to claim 1 or 2, characterized in that at least one luminescent reference mark (MR) is part of a reference sample (7-R) and that specific emission characteristics of said at least luminescent reference mark (MR) are measured, said emission specific characteristics include at least one excitation wavelength of said excitation pulse (P), at least one emission wavelength of said emission radiation (E) and reference intensity values (Vri - VRn) of emission intensity (I) at time intervals (ti - t „) for at least one of said emission wavelengths. Method according to claim 3, characterized in that the reference intensity values (VRi - VRn) and / or at least one function of the reference emission intensity versus time is / are stored in at least one. memory device (1c, 1d). Method according to claim 4, characterized in that said at least one function of reference intensity versus time emission is stored in a normalized and / or non-normalized form. Method according to any one of the preceding claims, characterized in that said light-emitting mark (MP) respectively the reference mark (MR) is excited with at least one excitation pulse (P) of at least an excitation source (3, 31 - 36) being a laser and / or an LED. Method according to any one of the preceding claims, characterized in that said luminescent probe marking (M-P) respectively the reference marking (M-R) is excited with at least one electron excitation pulse (P). A device for authenticating a luminescent test (MP) marking, comprising: at least one detector (4,41,42,4b) for measuring the test intensity (Vpi - Vpn) values of the emission intensity (I) ) from the emission radiation (E) of said luminescent probe (MP) marking in response to at least one excitation pulse (P) generated by at least one excitation source (3, 31 - 36) at time intervals. (ti - tn), further comprising at least one processor (1) for forming the intensity emission versus time test function of said test intensity values (Vpi - Vpn), at least one processor (1) to compare said intensity versus time emission function with at least one reference intensity versus time emission function, and at least one processor (1) to normalize said intensity versus time emission function of the test. proof before comparison with a function of the intensity emission versus time of the normalized reference test. A device for authenticating a glow reference mark (MR) comprising: at least one detector (4,41,42,4b) for measuring emission intensity reference (VR1 - VRn) values (I) the emission radiation (E) of said luminescent reference (MR) marking in response to at least one excitation pulse (P) generated by at least one excitation source (3, 31 - 36) at time intervals. (ti - tn) and further comprising at least one processor (1) for forming the intensity emission versus time reference function of said reference intensity values (VRi - VRn). Device according to Claim 8 or 9, characterized in that it comprises at least one memory device (1c, 1d) for storing emission intensity reference values (VRi - VRn) (I). at time intervals (ti - tn) for at least one wavelength of the emission radiation (E) of said luminescence reference mark (MR) and / or to store at least one function of the reference intensity versus time emission reference intensity values (VRi - VRn). Device according to any one of claims 8 to 10, characterized in that it comprises said at least one excitation source (3, 31 - 36). Device according to any one of claims 8 to 11, characterized in that said at least one detector (4) comprises a wavelength selector (4a '). Device according to any one of claims 8 to 12, characterized in that said at least one detector (4, 41,4b) converts the emission intensity (I) into electrical signals of the test intensity values. (Vpi - Vpn) respectively of the reference intensity values (VRi - VRn) and said at least one processor (1) samples said electrical signals to form a function of the intensity emission versus time of testing of said intensity values. (Vp-i - Vpn) respectively to form the intensity versus time of reference of the reference emission function of said reference intensity values (VR1 - VRn). Device according to any one of Claims 8 to 13, characterized in that it comprises at least one spectrometer for differentiating between two or more emission wavelengths and said at least one detector (4b). is a training photodetector for measuring emission radiation (E) at two or more emission wavelengths, allowing simultaneous measurement of the test intensity (Vpi - Vpn) values of emission radiation (E) of a luminescent (MP) tests a simultaneous measurement of the reference intensity values (VRi - VRn) of the emission radiation (E) of a luminescent reference marking (MR) respectively. Device according to claim 14, characterized in that said at least one formation photodetector (4b) is a two-dimensional CCD formation, a first row of photosensitive pixels (PIX) functions as a photodetection formation, The remaining rows of pixels function as a primary storage device for spectral information as a function of time through a line shift process. Security system for authentication of a luminescent test marking (MP), characterized in that it comprises: a device as defined in any one of claims 8 to 14, at least one reference sample (7-R) comprising at least least one luminescent reference mark (MR) for measuring reference intensity (Vri - VRn) values of emission intensity (I) in time intervals (ti - tn) for at least one emission radiation wavelength (E) said luminescent reference mark (MR) and at least one test sample (7-P) comprising at least one luminescent test mark (MP) for measuring test intensity values (VP1 - Vpn) of the emission (I) at time intervals (ti - tn) for at least one wavelength of the emission radiation (E) of said luminescent probe (MP). Security system according to claim 16, characterized in that at least one of said test sample (7-P) is part of a paint and / or coating composition of an article (7) to be authenticated. Security system according to claim 17, characterized in that at least one of said test samples (7-P) is contained in a loose material of an article (7) to be authenticated.